/Engine/Plugins/Runtime/XRBase/Source/XRBase/Public/HeadMountedDisplayFunctionLibrary.h
If the HMD has a positional sensor, this will return the game-world location of it, as well as the parameters for the bounding region of tracking. This allows an in-game representation of the legal positional tracking range. All values will be zeroed if the sensor is not available or the HMD does not support it.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintPure, Category="Input|HeadMountedDisplay", Meta=(AdvancedDisplay="LeftFOV,RightFOV,TopFOV,BottomFOV,Distance,NearPlane,FarPlane")) static void GetTrackingSensorParameters ( FVector & Origin, FRotator & Rotation, float & LeftFOV, float & RightFOV, float & TopFOV, float & BottomFOV, float & Distance, float & NearPlane, float & FarPlane, bool & IsActive, int32 Index )